mkent@violet.berkeley.edu (09/28/86)
[] Does anyone have any experience with analog to digital conversion on the Amiga? I'd like to set up a fairly generic unit which would accept a changing-voltage signal (e.g. the output of an audio amplifier) and generate 1 or 1-1/2 byte samples to be fed into either the parallel or serial port. I imagine being able to set a scaling factor (to allow for different ranges of input signals) and the sampling rate. Intuitively it seems to me this should be a fairly simple thing to assemble with off-the-shelf parts, but I don't really know a damn thing about hardware... I'd really appreciate suggestions about 1. how to build such a device, 2. where to look for information on how to build such a device, 3. where to buy such a device, ready-made, or 4. why this is an impossible task and I should forget about it Thanks much Marty Kent (mkent%violet@berkeley.edu) "Good judgement comes from experience. And experience comes from bad judgement."
wtm@neoucom.UUCP (Bill Mayhew) (10/01/86)
[[line eater food]] Hi, I've been using the audio digitizer made by Applied Visions for a couple of months. It plugs into the printer parallel port. It is "only" 8 bits, but after all, that matches the audio out from the Amiga correctly. The AV box supports recording on four tracks and can use as much memory as you have in Chip memory. I've taken samples that are up to 275K long. The input is only monaural, so you've got to take several passes for multiple tracks. It also allows you to scale, merge, and reverse the sound (actually any voltage signal) post hoc. The maximum sampling rate is around 21KHz, which is appropriate, given the rate of DMA sound output. I think anything higher would begin to interfere with the interrupts used by Intuition. The unit comes in a little beige box a little bigger than a cigarette package and attaches though a ribbon cable. A cheap microphone is included as well as an "RCA" pin style jack on the front panel for generic line level audio input. The included software permits saving the sound in 8SVX IFF single shot or three octave format, as well as in raw byte files. A spare db-25 jack is on the back of the box to facilitate attaching a printer. A lighted button on the front of the box indicates whether it is on or passing through to the printer. All in all, it was a reasonable deal for around $129 or so. My only complaint is that although the manual is complete enough to adequately operate the electronics and software, it stops short of explaining the 8SVX IFF format, etc. It would be nice, if for once, the instructions for one of these things would go beyond the dummy level. Some C language examples and Include files illustrating how to load raw or 8SVX files are included on the diskette. Bill Mayhew Division of Basic Medical Sciences Northeastern Ohio Universites College of Medicine Rootstown, OH 44272 USA phone 216-325-2511 (wtm@neoucom.UUCP)
hamilton@uiucuxc.CSO.UIUC.EDU (10/02/86)
wtm@neoucom.UUCP sez: > I've been using the audio digitizer made by Applied Visions >for a couple of months. >The maximum sampling rate is around 21KHz, ... >I think anything >higher would begin to interfere with the interrupts used by >Intuition. anything higher, or anything LOWER. alas, FutureSound disables interrupts and polls the parallel port & a timer channel. just try moving your mouse while sampling sometime. wayne hamilton U of Il and US Army Corps of Engineers CERL UUCP: {ihnp4,pur-ee,convex}!uiucdcs!uiucuxc!hamilton ARPA: hamilton%uiucuxc@a.cs.uiuc.edu USMail: Box 476, Urbana, IL 61801 CSNET: hamilton%uiucuxc@uiuc.csnet Phone: (217)333-8703 CIS: [73047,544] PLink: w hamilton